水星可能起源于稀有流星体
文章来源:未知 文章作者:enread 发布时间:2016-06-28 08:08 字体: [ ]  进入论坛
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Around 4.6 billion years ago, the universe was a chaos1 of collapsing2 gas and spinning debris3. Small particles of gas and dust clumped4 together into larger and more massive meteoroids that in turn smashed together to form planets. Scientists believe that shortly after their formation, these planets -- and particularly Mercury -- were fiery5 spheres of molten material, which cooled over millions of years. Now, geologists6 at MIT have traced part of Mercury's cooling history and found that between 4.2 and 3.7 billion years ago, soon after the planet formed, its interior temperatures plummeted7 by 240 degrees Celsius8, or 464 degrees Fahrenheit9
 
They also determined10, based on this rapid cooling rate and the composition of lava11 deposits on Mercury's surface, that the planet likely has the composition of an enstatite chondrite -- a type of meteorite12 that is extremely rare here on Earth. 
 
Timothy Grove13, the Cecil and Ida Green Professor of Geology in MIT's Department of Earth, Atmospheric14, and Planetary Sciences, says new information on Mercury's past is of interest for tracing Earth's early formation. 
 
"Here we are today, with 4.5 billion years of planetary evolution, and because the Earth has such a dynamic interior, because of the water we've preserved on the planet, [volcanism] just wipes out its past," Grove says. "On planets like Mercury, early volcanism is much more dramatic, and [once] they cooled down there were no later volcanic15 processes to wipe out the early history. This is the first place where we actually have an estimate of how fast the interior cooled during an early part of a planet's history."
 
Grove and his colleagues, including researchers from the University of Hanover, in Germany; the University of Liége, in Belgium; and the University of Bayreuth, in Germany, have published their results in Earth and Planetary Science Letters.


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1 chaos 7bZyz     
n.混乱,无秩序
参考例句:
  • After the failure of electricity supply the city was in chaos.停电后,城市一片混乱。
  • The typhoon left chaos behind it.台风后一片混乱。
2 collapsing 6becc10b3eacfd79485e188c6ac90cb2     
压扁[平],毁坏,断裂
参考例句:
  • Rescuers used props to stop the roof of the tunnel collapsing. 救援人员用支柱防止隧道顶塌陷。
  • The rocks were folded by collapsing into the center of the trough. 岩石由于坍陷进入凹槽的中心而发生褶皱。
3 debris debris     
n.瓦砾堆,废墟,碎片
参考例句:
  • After the bombing there was a lot of debris everywhere.轰炸之后到处瓦砾成堆。
  • Bacteria sticks to food debris in the teeth,causing decay.细菌附着在牙缝中的食物残渣上,导致蛀牙。
4 clumped 66f71645b3b7e2656cb3fe3b1cf938f0     
adj.[医]成群的v.(树、灌木、植物等的)丛、簇( clump的过去式和过去分词 );(土、泥等)团;块;笨重的脚步声
参考例句:
  • The bacteria clumped together. 细菌凝集一团。 来自《现代英汉综合大词典》
  • He clumped after her, up the stairs, into his barren office. 他拖着沉重的步伐跟在她的后面上楼了,走进了他那个空荡荡的诊所。 来自辞典例句
5 fiery ElEye     
adj.燃烧着的,火红的;暴躁的;激烈的
参考例句:
  • She has fiery red hair.她有一头火红的头发。
  • His fiery speech agitated the crowd.他热情洋溢的讲话激动了群众。
6 geologists 1261592151f6aa40819f7687883760a2     
地质学家,地质学者( geologist的名词复数 )
参考例句:
  • Geologists uncovered the hidden riches. 地质学家发现了地下的宝藏。
  • Geologists study the structure of the rocks. 地质学家研究岩石结构。
7 plummeted 404bf193ceb01b9d9a620431e6efc540     
v.垂直落下,骤然跌落( plummet的过去式和过去分词 )
参考例句:
  • Share prices plummeted to an all-time low. 股票价格暴跌到历史最低点。
  • A plane plummeted to earth. 一架飞机一头栽向地面。 来自《简明英汉词典》
8 Celsius AXRzl     
adj.摄氏温度计的,摄氏的
参考例句:
  • The temperature tonight will fall to seven degrees Celsius.今晚气温将下降到七摄氏度。
  • The maximum temperature in July may be 36 degrees Celsius.七月份最高温度可能达到36摄氏度。
9 Fahrenheit hlhx9     
n./adj.华氏温度;华氏温度计(的)
参考例句:
  • He was asked for the boiling point of water in Fahrenheit.他被问到水的沸点是华氏多少度。
  • The thermometer reads 80 degrees Fahrenheit.寒暑表指出华氏80度。
10 determined duszmP     
adj.坚定的;有决心的
参考例句:
  • I have determined on going to Tibet after graduation.我已决定毕业后去西藏。
  • He determined to view the rooms behind the office.他决定查看一下办公室后面的房间。
11 lava v9Zz5     
n.熔岩,火山岩
参考例句:
  • The lava flowed down the sides of the volcano.熔岩沿火山坡面涌流而下。
  • His anger spilled out like lava.他的愤怒像火山爆发似的迸发出来。
12 meteorite 2wNy1     
n.陨石;流星
参考例句:
  • The meteorite in Jilin Exhibition Hall is believed to be the largest in the world.吉林展览馆的陨石被认为是世界上最大的。
  • The famous Murchison meteorite smashed into the Australian ground in 1969.1969年著名的默奇森陨石轰然坠落在澳大利亚。
13 grove v5wyy     
n.林子,小树林,园林
参考例句:
  • On top of the hill was a grove of tall trees.山顶上一片高大的树林。
  • The scent of lemons filled the grove.柠檬香味充满了小树林。
14 atmospheric 6eayR     
adj.大气的,空气的;大气层的;大气所引起的
参考例句:
  • Sea surface temperatures and atmospheric circulation are strongly coupled.海洋表面温度与大气环流是密切相关的。
  • Clouds return radiant energy to the surface primarily via the atmospheric window.云主要通过大气窗区向地表辐射能量。
15 volcanic BLgzQ     
adj.火山的;象火山的;由火山引起的
参考例句:
  • There have been several volcanic eruptions this year.今年火山爆发了好几次。
  • Volcanic activity has created thermal springs and boiling mud pools.火山活动产生了温泉和沸腾的泥浆池。
TAG标签: planets mercury meteoroids
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